Selective Liquid-Liquid Extraction of Thorium(IV) from Rare-Earth Element Mixtures.

One of the major challenges in processing rare-earth element (REE) materials arises from the large amounts of radioactive thorium (Th) that are often found within REE minerals, encouraging enhanced metal separation procedures. We report here a study aimed at developing improved systems for REE processing with the goal of efficient extraction of Th(IV) from acidic solution. A tripodal ligand, TRPN-CMPO-Ph, was prepared that utilizes carbamoylmethylphosphine oxide (CMPO) chelators tethered to a tris(3-aminopropyl)amine (TRPN) capping scaffold. The ligand and its metal complexes were characterized by using elemental analysis, NMR, Fourier transform infrared spectroscopy, mass spectrometry, and luminescence spectroscopy. Using a liquid-liquid metal extraction protocol, TRPN-CMPO-Ph selectively extracts Th(IV) at an efficiency of 79% from a mixture of Th(IV), UO22+, and all rare-earth metal cations (except promethium) dissolved in nitric acid into an organic solvent. Th(IV) extraction selectivity is maintained upon extraction from a mixture that approximates a typical monazite leach solution containing several relevant lanthanide ions, including two ions at higher concentration relative to Th(IV). Comparative studies with a tris(2-aminoethyl)amine (TREN)-capped derivative are presented and support the need for a larger TRPN capping scaffold in achieving Th(IV) extraction selectivity.

The Synthesis of Functionalized 3-Aryl- and 3-Heteroaryloxazolidin-2-ones and Tetrahydro-3-aryl-1,3-oxazin-2-ones via the Iodocyclocarbamation Reaction: Access to Privileged Chemical Structures and Scope and Limitations of the Method.

3-Aryl- and 3-heteroaryloxazolidin-2-ones, by virtue of the diverse pharmacologic activities exhibited by them after subtle changes to their appended substituents, are becoming increasingly important and should be considered privileged chemical structures. The iodocyclocarbamation reaction has been extensively used to make many 3-alkyl-5-(halomethyl)oxazolidin-2-ones, but the corresponding aromatic congeners have been relatively underexplored. We suggest that racemic 3-aryl- and 3-heteroaryl-5-(iodomethyl)oxazolidin-2-ones, readily prepared by the iodocyclocarbamation reaction of N-allylated N-aryl or N-heteroaryl carbamates, may be useful intermediates for the rapid preparation of potential lead compounds with biological activity. We exemplify this point by using this approach to prepare racemic linezolid, an antibacterial agent. Herein, we report the results of our systematic investigation into the scope and limitations of this process and have identified some distinguishing characteristics within the aryl/heteroaryl series. We also describe the first preparation of 3-aryloxazolidin-2-ones bearing new functionalized C-5 substituents derived from conjugated 1,3-dienyl and cumulated 1,2-dienyl carbamate precursors. Finally, we describe the utility of the iodocyclocarbamation reaction for making six-membered tetrahydro-3-aryl-1,3-oxazin-2-ones.

Two Beta-Phosphorylamide Compounds as Ligands for Sm3+, Eu3+, and Tb3+: X-ray Crystallography and Luminescence Properties.

This paper describes the synthesis of two beta-phosphorylamide ligands and their coordination chemistry with the Ln ions Tb3+, Eu3+, and Sm3+. Both the ligands and Ln complexes were characterized by IR, NMR, MS, and X-ray crystallography. The luminescence properties of the Tb3+ and Eu3+ complexes were also characterized, including the acquisition of lifetime decay curves. In the solid state, the Tb3+ and Sm3+ ligand complexes were found to have a 2:2 stoichiometry when analyzed by X-ray diffraction. In these structures, the Ln ion was bound by both oxygen atoms of each beta-phosphorylamide moiety of the ligands. The Tb3+ and Eu3+ complexes were modestly emissive as solutions in acetonitrile, with lifetime values that fell within typical ranges.

Assembly of a mononuclear ferrous site using a bulky aldehyde-imidazole ligand.

A new iron(II) complex has been prepared and characterized. [Fe(TrImA)2(OTf)2] (1, TrImA = 1-Tritylimidazole-4-carboxaldehyde). The solid state structure of 1 has been determined by X-ray crystallography. Compound 1 crystallizes in monoclinic space group P21/c, with a = 10.8323(18) Å, b = 8.1606(13) Å and c = 24.818(4) Å. The iron center is coordinated to two imidazole groups, two pendant aldehyde-derived carbonyl oxygens and two triflate oxygens. The complex is high spin between 300 and 20 K as indicated by variable field variable temperature magnetic measurements. A fit of the magnetic data yielded g = 2.17 and D = 4.05 cm-1. A large HOMO-LUMO gap energy (4.49 eV) exists for 1 indicating high stability.

Crystal structure of a samarium(III) nitrate chain cross-linked by a bis-carbamoyl-methyl-phosphine oxide ligand.

In the title compound poly[aqua-bis-(µ-nitrato-κ(4) O,O':O,O'')tetra-kis-(nitrato-κ(2) O,O'){µ4-tetra-ethyl [(ethane-1,2-diyl)bis(aza-nedi-yl)bis-(2-oxo-ethane-2,1-di-yl)]di-phospho-nate-κ(2) O,O'}disamarium(III)], [Sm2(NO3)6(C14H30N2O8P2)(H2O)] n , a 12-coordinate Sm(III) and a nine-coordinate Sm(III) cation are alternately linked via shared bis-bidentate nitrate anions into a corrugated chain extending parallel to the a axis. The nine-coordinate Sm(III) atom of this chain is also chelated by a bidentate, yet flexible, carbamoyl-methyl-phoshine oxide (CMPO) ligand and bears one water mol-ecule. This water mol-ecule is hydrogen bonded to nitrate groups bonded to the 12-coordinate Sm(III) cation. The CMPO ligand, which lies about an inversion center, links neighboring chains along the c axis, forming sheets parallel to the ac plane. Hydrogen bonds between the amide NH group and metal-bound nitrate anions are also present in these sheets. The sheets are packed along the b axis through only van der Waals inter-actions.

Crystal structure of [propane-1,3-diylbis(piperidine-4,1-di-yl)]bis-[(pyridin-4-yl)methanone]-isophthalic acid (1/1).

In the crystal structure of the title co-crystal, C25H32N4O2·C8H6O4, isophthalic acid and [propane-1,3-diylbis(piperidine-4,1-di-yl)]bis-(pyridin-4-yl-methanone) mol-ecules are connected into supra-molecular chains aligned along the c axis by O-H⋯N hydrogen bonding. These aggregate into supra-molecular layers oriented parallel to the ac plane by C-H⋯O inter-actions. These layers then stack in an ABCD pattern along the b-axis direction by additional C-H⋯O inter-actions to give the full three-dimensional crystal structure. The central chain in the di-pyridyl-amide molecule has an anti-gauche conformation.

Crystal structure of penta-kis-(ethyl-enedi-amine-κ(2) N,N')lanthanum(III) trichloride-ethylene-diamine-dichloromethane (1/1/1).

We report here the crystal structure of a ten-coordinate lanthanum(III) metal coordinated by five bidentate ethyl-enedi-amine ligands, [La(C2H8N2)5]Cl3·C2H8N2·CH2Cl2. One free ethyl-enedi-amine mol-ecule and three Cl(-) anions are also located in the asymmetric unit. The overall structure is held together by an extensive hydrogen-bonding network between the Cl(-) anions and the NH groups on the metal-bound ethyl-enedi-amine ligands. The free ethyl-enedi-amine mol-ecule is held in an ordered position by additional hydrogen bonds involving both the chlorides and -NH groups on the metal-bound ligands. One highly disordered mol-ecule of di-chloro-methane is located on an inversion center; however, all attempts to model this disorder were unsuccessful. The electron density in this space was removed using the BYPASS procedure [van der Sluis & Spek (1990 ▶). Acta Cryst. A46, 194-201].

Three derivatives of phenacyldiphenylphosphine oxide: influence of aromatic and alkyl substituents on the luminescence sensitization of four Ln(NO3)3 salts.

A series of four ß-carbonylphosphine oxide compounds have been synthesized, and their complexes with the nitrate salts of Sm3+, Eu3+, Tb3+ and Dy3+ have been characterized in solution and in the solid state. Analysis of the complexes using IR and NMR suggests that metal-ligand binding occurs mainly through the phosphine oxide group of the ligand, with some involvement of the carbonyl group. All 16 complexes luminesce in solutions of acetonitrile, albeit with varying degrees of intensity. The highest quantum yield values obtained for this series are those where the ligand contains an aryl carbonyl group paired with an electron rich phosphine oxide group (29.8 and 11% for the Tb3+ and Eu3+ complexes, respectively). In contrast, the longest emission lifetime values were found for complexes where the ligand contains a bulky substituent on the carbonyl group paired with an electron rich phosphine oxide (1.86, 1.402, 0.045 ms for the Tb3+, Eu3+ and Sm3+ complexes, respectively).

Crystal structure of tert-butyl 3,6-di-iodo-carbazole-9-carboxyl-ate.

The mol-ecular structure of tert-butyl 3,6-di-iodo-carbazole-9-carboxyl-ate, C17H15I2NO2, features a nearly planar 13-membered carbazole ring with C-I bond lengths of 2.092 (4) and 2.104 (4) Å. The carbamate group has key bond lengths of 1.404 (6) Š(N-C), 1.330 (5) Š(O-C), and 1.201 (6) Š(C=O). The crystal contains inter-molecular π-π inter-actions, as well as both type I and type II inter-molecular I⋯I inter-actions.

Crystal structure of a (carb-oxy-meth-yl)tri-ethyl-aza-nium bromide-2-(tri-ethyl-aza-n-ium-yl)acetate (1/1) hydrogen-bonded dimer.

The title compound, C8H18NO2 +·Br-·C8H17NO2, crystallizes as the bromide salt of a 50:50 mixture of (tri-ethyl-azaniumyl)-carb-oxy-lic acid and the zwitterionic (tri-ethyl-azaniumyl)-carboxyl-ate. The two organic entities are linked by a half-occupied bridging carb-oxy-lic acid hydrogen atom that is hydrogen-bonded to the carboxyl-ate group of the second mol-ecule. The tetra-lkyl-ammonium group adopts a nearly perfect tetra-hedral shape around the nitro-gen atom with bond lengths that agree with known values. The carb-oxy-lic acid/carboxyl-ate group is oriented anti to one of the ethyl groups on the ammonium group, and the carbonyl oxygen atom is engaged in intra-molecular C-H⋯O hydrogen bonds.

Crystal structures of (Z)-(ethene-1,2-di-yl)bis-(di-phenyl-phosphine sulfide) and its complex with PtII dichloride.

The crystal structures of (Z)-(ethene-1,2-di-yl)bis-(di-phenyl-phosphine sulfide), C26H22P2S2 (I), along with its complex with PtII dichloride, di-chlorido[(Z)-(ethene-1,2-di-yl)bis-(di-phenyl-phosphine sulfide)-κ2 S,S']platinum(II), [PtCl2(C26H22P2S2)] (II), are described here. Compound I features P=S bond lengths of 1.9571 (15) and 1.9529 (15) Å, with a torsion angle of 166.24 (7)° between the two phosphine sulfide groups. The crystal of compound I features both intra-molecular C-H⋯S hydrogen bonds and π-π inter-actions. Mol-ecules of compound I are held together with inter-molecular π-π and C-H⋯π inter-actions to form chains that run parallel to the z-axis. The inter-molecular C-H⋯π inter-action has a H⋯Cg distance of 2.63 Å, a D⋯Cg distance of 3.573 (5) Šand a D-H⋯Cg angle of 171° (where Cg refers to the centroid of one of the phenyl rings). These chains are linked by relatively long C-H⋯S hydrogen bonds with D⋯A distances of 3.367 (4) and 3.394 (4) Šwith D-H⋯A angles of 113 and 115°. Compound II features Pt-Cl and Pt-S bond lengths of 2.3226 (19) and 2.2712 (19) Å, with a P=S bond length of 2.012 (3) Å. The PtII center adopts a square-planar geometry, with Cl-Pt-Cl and S-Pt-S bond angles of 90.34 (10) and 97.19 (10)°, respectively. Mol-ecules of compound II are linked in the crystal by inter-molecular C-H⋯Cl and C-H⋯S hydrogen bonds.

A mixed phosphine sulfide/selenide structure as an instructional example for how to evaluate the quality of a model.

This paper compares variations on a structure model derived from an X-ray diffraction data set from a solid solution of chalcogenide derivatives of cis-1,2-bis-(di-phenyl-phosphan-yl)ethyl-ene, namely, 1,2-(ethene-1,2-di-yl)bis-(di-phenyl-phoshpine sulfide/selenide), C26H22P2S1.13Se0.87. A sequence of processes are presented to ascertain the composition of the crystal, along with strategies for which aspects of the model to inspect to ensure a chemically and crystallographically realistic structure. Criteria include mis-matches between F obs 2 and F calc 2, plots of |F obs| vs |F calc|, residual electron density, checkCIF alerts, pitfalls of the OMIT command used to suppress ill-fitting data, comparative size of displacement ellipsoids, and critical inspection of inter-atomic distances. Since the structure is quite small, solves easily, and presents a number of readily expressible refinement concepts, we feel that it would make a straightforward and concise instructional piece for students learning how to determine if their model provides the best fit for the data and show students how to critically assess their structures.

Crystal structure of chlorido-[diphen-yl(thio-phen-2-yl)phosphine-κP]gold(I).

The crystal structure of the title compound, [AuCl(C16H13PS)], is reported. The mol-ecular structure features a nearly linear arrangement of the chloride and phosphino ligands around the gold(I) center, with a P-Au-Cl bond angle of 179.42 (9)°. The Au-P and Au-Cl bond lengths are 2.226 (2) and 2.287 (2) Å, respectively. The geometry of the groups bonded to the phospho-rus atom of the ligand is a slightly distorted tetra-hedron. The phenyl and thienyl rings of the ligand are extensively disordered, with the thienyl refined over all three possible positions on the phospho-rus atom. The relative occupancy ratio between these positions was found to be 0.406 (3):0.406 (2):0.188 (2). One of the major thienyl ring positions with the relative occupancy of 0.406 was modeled as two rotational isomers around the C-P bond with a relative occupancy ratio of 0.278 (3):0.128 (3). Inter-molecular C-H⋯π inter-actions present in the crystal lattice link mol-ecules of the title compound together to form a complex three-dimensional network.

Synthesis of diphenyl-(2-thienyl)phosphine, its chalcogenide derivatives and a series of novel complexes of lanthanide nitrates and triflates.

A novel synthesis of diphenyl(2-thienyl)phosphine, along with its' oxide, sulfide and selenide derivatives, is reported here. These phosphines have been characterized by NMR, IR, MS and X-Ray crystallography. The phosphine oxide derivative was reacted with a selection of lanthanide(III) nitrates and triflates, LnX3, to give the resultant metal-ligand complexes. These complexes have also been characterized by NMR, IR, MS and X-Ray crystallography. Single crystal X-Ray diffraction data shows a difference in metal-ligand complex stoichiometry and stereochemistry depending on the counteranion (nitrate vs. triflate). The [Ln(Ar3PO)3(NO3)3] ligand-nitrate complexes are nine-coordinate to the metal in the solid state (bidentate nitrate), featuring a 1 : 3 lanthanide-ligand ratio and bear an overall octahedral arrangement of the six, coordinated ligands. Our [Ln(Ar3PO)3(NO3)3] ligand-nitrate complexes gave three examples of fac-stereochemistry, where mer-stereochemistry is almost universally observed in the literature of highly related [Ln(Ar3PO)3(NO3)3] complexes. For the Tb complexes, two different arrangements of the ligands around the metal were observed in the solid state for [Tb(Ar3PO)3(NO3)3] and [Tb(Ar3PO)4(OTf)2] [OTf]. [Tb(Ar3PO)3(NO3)3] is strictly nine-coordinate, ligand mer-stereochemistry in the solid state, and [Tb(Ar3PO)4(OTf)2] [OTf] is strictly octahedral, six-coordinate, with a square-planar stereochemical arrangement of the phosphine oxide ligands around the metal.

Crystal structure of N,N-diisopropyl-4-methyl-benzene-sulfonamide.

The synthesis of the title compound, C13H21NO2S, is reported here along with its crystal structure. This compound crystallizes with two mol-ecules in the asymmetric unit. The sulfonamide functional group of this structure features S=O bond lengths ranging from 1.433 (3) to 1.439 (3) Å, S-C bond lengths of 1.777 (3) and 1.773 (4) Å, and S-N bond lengths of 1.622 (3) and 1.624 (3) Å. When viewing the mol-ecules down the S-N bond, the isopropyl groups are gauche to the aromatic ring. On each mol-ecule, two methyl hydrogen atoms of one isopropyl group are engaged in intra-molecular C-H⋯O hydrogen bonds with a nearby sulfonamide oxygen atom. Inter-molecular C-H⋯O hydrogen bonds and C-H⋯π inter-actions link mol-ecules of the title compound in the solid state.

Crystal structure of 4-methyl-N-(4-methyl-benz-yl)benzene-sulfonamide.

The title compound, C15H17NO2S, was synthesized via a substitution reaction between 4-methyl-benzyl-amine and p-toluene-sulfonyl chloride. In the crystal, N-H⋯O hydrogen bonds link the mol-ecules, forming ribbons running along the b-axis direction. One of the aromatic rings hosts two inter-molecular C-H⋯π inter-actions that link these hydrogen-bonded ribbons into a three-dimensional network.

Crystal structure of 1-[(4-methylbenzene)sulfonyl]pyrrolidine.

The mol-ecular structure of the title compound, C11H15NO2S, features a sulfonamide group with S=O bond lengths of 1.4357 (16) and 1.4349 (16) Å, an S-N bond length of 1.625 (2) Å, and an S-C bond length of 1.770 (2) Å. When viewing the mol-ecule down the S-N bond, both N-C bonds of the pyrrolidine ring are oriented gauche to the S-C bond with torsion angles of -65.6 (2)° and 76.2 (2)°. The crystal structure features both intra- and inter-molecular C-H⋯O hydrogen bonds, as well as inter-molecular C-H⋯π and π-π inter-actions, leading to the formation of sheets parallel to the ac plane.

Crystal structure of 4-methyl-N-propyl-benzene-sulfonamide.

The crystal structure of the title sulfonamide, C10H15NO2S, comprises two mol-ecules in the asymmetric unit. The S=O bond lengths of the sulfonamide functional group range from 1.428 (2) to 1.441 (2) Å, with S-C bond lengths of 1.766 (3) Š(for both mol-ecules in the asymmetric unit), and S-N bond lengths of 1.618 (2) and 1.622 (3) Å, respectively. When both mol-ecules are viewed down the N-S bond, the propyl group is gauche to the toluene moiety. In the crystal structure, mol-ecules of the title compound are arranged in an intricate three-dimensional network that is formed via inter-molecular C-H⋯O and N-H⋯O hydrogen bonds. The crystal structure was refined from a crystal twinned by inversion.

Syntheses and crystal structures of the anhydride 4-oxa-tetra-cyclo-[5.3.2.02,6.08,10]dodec-11-ene-3,5-dione and the related imide 4-(4-bromo-phen-yl)-4-aza-tetra-cyclo-[5.3.2.02,6.08,10]dodec-11-ene-3,5-dione.

The syntheses and crystal structures of the two title compounds, C11H10O3 (I) and C17H14BrNO2 (II), both containing the bi-cyclo-[2.2.2]octene ring system, are reported here [the structure of I has been reported previously: White & Goh (2014 ▸). Private Communication (refcode HOKRIK). CCDC, Cambridge, England]. The bond lengths and angles of the bi-cyclo-[2.2.2]octene ring system are similar for both structures. The imide functional group of II features carbonyl C=O bond lengths of 1.209 (2) and 1.210 (2) Å, with C-N bond lengths of 1.393 (2) and 1.397 (2) Å. The five-membered imide ring is nearly planar, and it is positioned exo relative to the alkene bridgehead carbon atoms of the bi-cyclo-[2.2.2]octene ring system. Non-covalent inter-actions present in the crystal structure of II include a number of C-H⋯O inter-actions. The extended structure of II also features C-H⋯O hydrogen bonds as well as C-H⋯π and lone pair-π inter-actions, which combine together to create supra-molecular sheets.

Crystal structures of two bis-carbamoyl-methyl-phosphine oxide (CMPO) compounds.

Two bis-carbamoyl-methyl-phosphine oxide compounds, namely {[(3-{[2-(di-phen-yl-phosphino-yl)ethanamido]-meth-yl}benz-yl)carbamo-yl]meth-yl}di-phenyl-phos-phine oxide, C36H34N2O4P2, (I), and diethyl [({2-[2-(di-eth-oxy-phosphino-yl)ethanamido]-eth-yl}carbamo-yl)meth-yl]phospho-nate, C14H30N2O8P2, (II), were synthesized via nucleophilic acyl substitution reactions between an ester and a primary amine. Hydrogen-bonding inter-actions are present in both crystals, but these inter-actions are intra-molecular in the case of compound (I) and inter-molecular in compound (II). Intra-molecular π-π stacking inter-actions are also present in the crystal of compound (I) with a centroid-centroid distance of 3.9479 (12) Šand a dihedral angle of 9.56 (12)°. Inter-molecular C-H⋯π inter-actions [C⋯centroid distance of 3.622 (2) Å, C-H⋯centroid angle of 146°] give rise to supra-molecular sheets that lie in the ab plane. Key geometric features for compound (I) involve a nearly planar, trans-amide group with a C-N-C-C torsion angle of 169.12 (17)°, and a torsion angle of -108.39 (15)° between the phosphine oxide phospho-rus atom and the amide nitro-gen atom. For compound (II), the electron density corresponding to the phosphoryl group was disordered, and was modeled as two parts with a 0.7387 (19):0.2613 (19) occupancy ratio. Compound (II) also boasts a trans-amide group that approaches planarity with a C-N-C-C torsion angle of -176.50 (16)°. The hydrogen bonds in this structure are inter-molecular, with a D⋯A distance of 2.883 (2) Šand a D-H⋯A angle of 175.0 (18)° between the amide hydrogen atom and the P=O oxygen atom. These non-covalent inter-actions create ribbons that run along the b-axis direction.